import os
import shutil
import tempfile
from atomicwrites import AtomicWriter

def mkdirs_exists_ok(path):
  try:
    os.makedirs(path)
  except OSError:
    if not os.path.isdir(path):
      raise

def rm_not_exists_ok(path):
  try:
    os.remove(path)
  except OSError:
    if os.path.exists(path):
      raise

def rm_tree_or_link(path):
  if os.path.islink(path):
    os.unlink(path)
  elif os.path.isdir(path):
    shutil.rmtree(path)

def get_tmpdir_on_same_filesystem(path):
  # TODO(mgraczyk): HACK, we should actually check for which filesystem.
  normpath = os.path.normpath(path)
  parts = normpath.split("/")
  if len(parts) > 1:
    if parts[1].startswith("raid"):
      if len(parts) > 2 and parts[2] == "runner":
        return "/{}/runner/tmp".format(parts[1])
      elif len(parts) > 2 and parts[2] == "aws":
        return "/{}/aws/tmp".format(parts[1])
      else:
        return "/{}/tmp".format(parts[1])
    elif parts[1] == "aws":
      return "/aws/tmp"
    elif parts[1] == "scratch":
      return "/scratch/tmp"
  return "/tmp"

class AutoMoveTempdir(object):
  def __init__(self, target_path, temp_dir=None):
    self._target_path = target_path
    self._path = tempfile.mkdtemp(dir=temp_dir)

  @property
  def name(self):
    return self._path

  def close(self):
    os.rename(self._path, self._target_path)

  def __enter__(self): return self

  def __exit__(self, type, value, traceback):
    if type is None:
      self.close()
    else:
      shutil.rmtree(self._path)

class NamedTemporaryDir(object):
  def __init__(self, temp_dir=None):
    self._path = tempfile.mkdtemp(dir=temp_dir)

  @property
  def name(self):
    return self._path

  def close(self):
    shutil.rmtree(self._path)

  def __enter__(self): return self

  def __exit__(self, type, value, traceback):
    self.close()

def _get_fileobject_func(writer, temp_dir):
  def _get_fileobject():
    file_obj = writer.get_fileobject(dir=temp_dir)
    os.chmod(file_obj.name, 0o644)
    return file_obj
  return _get_fileobject

def atomic_write_on_fs_tmp(path, **kwargs):
  """Creates an atomic writer using a temporary file in a temporary directory
     on the same filesystem as path.
  """
  # TODO(mgraczyk): This use of AtomicWriter relies on implementation details to set the temp
  #                 directory.
  writer = AtomicWriter(path, **kwargs)
  return writer._open(_get_fileobject_func(writer, get_tmpdir_on_same_filesystem(path)))


def atomic_write_in_dir(path, **kwargs):
  """Creates an atomic writer using a temporary file in the same directory
     as the destination file.
  """
  writer = AtomicWriter(path, **kwargs)
  return writer._open(_get_fileobject_func(writer, os.path.dirname(path)))

